1. Field of the Invention
The invention relates to a method for the repair of the refractory lining of the wall of a shaft furnace, which has a steel shell, a worn residual refractory lining and cooling plates for coolant flow extending through the shell into the refractory lining. The method will be described and illustrated in particular with reference to an application in a blast furnace for preparing pig iron, but the invention is equally applicable to other shaft furnaces of the type indicated. The invention extends to a shaft furnace repaired by the method.
2. Description of the Prior Art
A common design for a blast furnace is of the type described above. In such a furnace the service life of the refractory wall lining is extended by cooling the lining by means of the cooling plates with water flowing through them. These cooling plates generally have a flat shape, so that as well as their cooling function they also have the function of anchoring the brickwork. The cooling plates are in horizontal rings. The spacing of the plates in these rings, and the vertical spacing of the rings, is here referred to as the pitch of the cooling plate pattern.
During the campaign of a blast furnace which may last many years, the lining is subject to continuous corrosion and erosion, whereby the protection of the shell by this lining is steadily lessened. At the end of a campaign the residual lining may have a very erratic profile and in places may even have almost disappeared entirely. The furnace is taken out of service and provided with a new lining.
The most radical repair consists in that the entire residual lining is removed and an original new lining is fitted. This has various drawbacks. Since the refractory lining is often made from expensive materials, in some places for example from graphite, semi-graphite or silicon carbide, the removal of the residual lining means a considerable capital loss. Fitting a new lining also takes a long time, since in particular it must be built up completely from bricks and blocks shaped to fit. Some of these shapes may only be made when, after the furnace has cooled down, the exact dimensions of the furnace can be measured. It will be clear that fitting an entirely new lining is not only expensive, but moreover is associated with much wasted time representing considerable loss of production by the furnace.
Proposals are known for achieving interim repairs to furnaces by injecting or compacting mass onto the places where the lining is the most worn, but it has been found that such repairs have only limited durability and that in the course of time more radical repairs are still needed.